To ensure security against vehicle theft, many vehicles include a steering lock device, which is capable of locking the steering wheel. This type of a steering lock device is usually electrically driven and includes a lock member, which is shifted by a motor or the like from an unlock position to a lock position to lock the steering wheel. Japanese Laid-Open Patent Publication No. 2012-25269 describes the arrangement of magnetic sensors at a lock position and an unlock position to detect whether the lock member is located in the lock position or the unlock position.